To test the in vivo tumor suppressive role of miR‐34c in OS pathogenesis, we crossed transgenic mice overexpressing miR‐34c in osteoblasts (Col1a1 2.3kb‐miR‐34c) to mice deficient for p53 in osteoblasts (Col1a1 rat 2.3kb Cre; p53f/f or p53 cKO). The gene discussed is COL1A1; the disease is neoplasm.